Memory units can be arranged in various manners. Some memory management schemes associate a validity tag or validity bit with each memory segment in order to indicate whether that memory segment stores valid data. This memory management scheme can be implemented in cache memory units but this is not necessarily so.
Typically, a multiple-bit information vector indicates which data segments out a sequence of memory segments are valid. The segment can include one or more memory entries.
After a certain memory segment is read it should be labeled invalid, thus the corresponding bit should be reset.
If, for example, the memory segments represented by the information vectors are stored in a consecutive manner then the locations of the corresponding bits within the vectors indicate where these memory segments are located.
Typically, in order to fetch a memory segment and update the information vector three instructions were required. The following exemplary code illustrates these three instructions: (i) find first set bit in information vector and store the position value in a register; (ii) clear the first set bit, and (iii) multiply the content of the register by a multiplication factor to find the location of memory segment that corresponds to the first bit. The execution of these instructions requires many processor cycles and slow down the execution of a very commonly executed set of instructions.
There is a need to provide efficient methods for performing a plurality of bit operations and devices having a plurality of bit operations capability.